Kotaeo tsosa



OFFICE.

KOTARO KOI' I'AGAI, 0F TOKYO, JAPAN.

WATERPROOF PAPER.

No Drawing.

and other containers, and consists in first immersing in a bath of gelatin solution the paper to be tre ted, making the solution insoluble by app ying' thereon a mixed solution of chrome alum solutionand ammoniacal alumsolution, and subsequently coating the paper with a second mixture consisting of castor oil, tung oil and lead or zinc salt, as hereinafter described and claimed. The invention has for its object to obtain an impermeable'paper which is smooth and with: out wrinkles and which has the resistance required for the purpose for which it is to be used, and which is water-proof in character. i I

In carrying out my'inv'ention, a sheet of paper is first coated with vegetable paste, preferably brackenpaste, and is then im mersed in a bath of gelatin solution, This bracken paste is made of the root of the edible fern, known as bracken, especially the Ptem's 05 mm This root is firstly dried, ground to powder, mixed with water, and finally filtered'through cottonto precipitate a sticky mass of paste. When the sheet is completely impregnated, I proceed to coatit with a mixture of chrome alum solution and ammoniacal solution, in .order to make further adding thereto 5 grams of iron oxid,

and finally heating it to a temperature between 180 and 200 degrees Fahrenheit for Specification of Letters Patent. Patented June 24, 1919, Application filed November 8, 1918. Serial No. 261,689. I

' about one half of an hour. The mixture thus prepared, which may be diluted with pine oil, is then applied in an appropriate manner over the base hereinbefore described.

In order to insure success in the treatmen of the paper and to attain the most eflicient result, I cause the said mixture already applied upon the base to be covered with an additional layer of a compound which I prepare by mixing 5 grams of castor oil with 5 grams of white lead, heating it for about one half of an hour to a temperature preferably slightly lower than200 degrees Fahrenheit, adding thereto 10 grams of zinc oxid, 20 grams of tung oil, 15 grams of boiled linseed oil, subsequently heating to a temperature between 180 and 200 degrees Fahrenheit for about2 hours, which, when due 'to its speedy drying nature, which de- 7 feet I am enabled to overcome by moderating to the required extent the drying erty ofthe added.

What I claim is The process of making paper impermeable to water, and which consists in covering the vpaper with gelatin solution rendering P P" oil before the proper-dmers are the gelatin insoluble, then coating with a,

mixture ofcastor oil, lead oxid, tung oil and iron oxid, and subsequently coating over the said mixture with a second mixture consisting of castor oil, white lead, zinc oxid, tung oil and linseed oil. In testimony whereof I aflix my slgnature in the presence of two witnesses.

KOTARO KO-NAGAI. 1,. 8.] 7

Witnesses:

' II. MeD. 'Gnnommz,

H. Yssmmm. 

